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Hi,
attached is the promised cleanup/bugfix patch for the slab bootstrap:
Changes:
- kmem_cache_init & kmem_cache_sizes_init merged into one function,
called after mem_init(). It's impossible to bring slab to an operational
state without working gfp, thus the early partial initialization is not
necessary.
- g_cpucache_up set to FULL at the end of kmem_cache_init instead of the
module init call. This is a bugfix: slab was completely initialized,
just the update of the state was missing.
- some documentation for the bootstrap added.
Patch against 2.5.69-mm1, tested with UP and SMP on i386 (with
s/read_lock/spin_lock/ in filetable.c).
Andrew, what do you think? The minimal fix for the bug is a two-liner:
move g_cpucache_up=FULL from cpucache_init to kmem_cache_sizes_init, but
I want to get rid of kmem_cache_sizes_init, too.
--
Manfred
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filename="patch-slab-FULL"
// $Header$
// Kernel Version:
// VERSION = 2
// PATCHLEVEL = 5
// SUBLEVEL = 69
// EXTRAVERSION = -mm1
--- 2.5/include/linux/slab.h 2003-05-05 20:27:16.000000000 +0200
+++ build-2.5/include/linux/slab.h 2003-05-06 21:04:24.000000000 +0200
@@ -49,7 +49,6 @@
/* prototypes */
extern void kmem_cache_init(void);
-extern void kmem_cache_sizes_init(void);
extern kmem_cache_t *kmem_find_general_cachep(size_t, int gfpflags);
extern kmem_cache_t *kmem_cache_create(const char *, size_t, size_t, unsigned long,
--- 2.5/mm/slab.c 2003-05-06 21:01:42.000000000 +0200
+++ build-2.5/mm/slab.c 2003-05-06 21:17:57.000000000 +0200
@@ -571,11 +571,40 @@
return cachep->array[smp_processor_id()];
}
-/* Initialisation - setup the `cache' cache. */
+/* Initialisation.
+ * Called after the gfp() functions have been enabled, and before smp_init().
+ */
void __init kmem_cache_init(void)
{
size_t left_over;
+ struct cache_sizes *sizes;
+ struct cache_names *names;
+
+ /*
+ * Fragmentation resistance on low memory - only use bigger
+ * page orders on machines with more than 32MB of memory.
+ */
+ if (num_physpages > (32 << 20) >> PAGE_SHIFT)
+ slab_break_gfp_order = BREAK_GFP_ORDER_HI;
+
+ /* Bootstrap is tricky, because several objects are allocated
+ * from caches that do not exist yet:
+ * 1) initialize the cache_cache cache: it contains the kmem_cache_t
+ * structures of all caches, except cache_cache itself: cache_cache
+ * is statically allocated.
+ * Initially an __init data area is used for the head array, it's
+ * replaced with a kmalloc allocated array at the end of the bootstrap.
+ * 2) Create the first kmalloc cache.
+ * The kmem_cache_t for the new cache is allocated normally. An __init
+ * data area is used for the head array.
+ * 3) Create the remaining kmalloc caches, with minimally sized head arrays.
+ * 4) Replace the __init data head arrays for cache_cache and the first
+ * kmalloc cache with kmalloc allocated arrays.
+ * 5) Resize the head arrays of the kmalloc caches to their final sizes.
+ */
+
+ /* 1) create the cache_cache */
init_MUTEX(&cache_chain_sem);
INIT_LIST_HEAD(&cache_chain);
list_add(&cache_cache.next, &cache_chain);
@@ -589,27 +618,10 @@
cache_cache.colour = left_over/cache_cache.colour_off;
cache_cache.colour_next = 0;
- /* Register a cpu startup notifier callback
- * that initializes ac_data for all new cpus
- */
- register_cpu_notifier(&cpucache_notifier);
-}
-
-/* Initialisation - setup remaining internal and general caches.
- * Called after the gfp() functions have been enabled, and before smp_init().
- */
-void __init kmem_cache_sizes_init(void)
-{
- struct cache_sizes *sizes = malloc_sizes;
- struct cache_names *names = cache_names;
-
- /*
- * Fragmentation resistance on low memory - only use bigger
- * page orders on machines with more than 32MB of memory.
- */
- if (num_physpages > (32 << 20) >> PAGE_SHIFT)
- slab_break_gfp_order = BREAK_GFP_ORDER_HI;
+ /* 2+3) create the kmalloc caches */
+ sizes = malloc_sizes;
+ names = cache_names;
while (sizes->cs_size) {
/* For performance, all the general caches are L1 aligned.
@@ -638,10 +650,7 @@
sizes++;
names++;
}
- /*
- * The generic caches are running - time to kick out the
- * bootstrap cpucaches.
- */
+ /* 4) Replace the bootstrap head arrays */
{
void * ptr;
@@ -660,29 +669,42 @@
malloc_sizes[0].cs_cachep->array[smp_processor_id()] = ptr;
local_irq_enable();
}
+
+ /* 5) resize the head arrays to their final sizes */
+ {
+ kmem_cache_t *cachep;
+ down(&cache_chain_sem);
+ list_for_each_entry(cachep, &cache_chain, next)
+ enable_cpucache(cachep);
+ up(&cache_chain_sem);
+ }
+
+ /* Done! */
+ g_cpucache_up = FULL;
+
+ /* Register a cpu startup notifier callback
+ * that initializes ac_data for all new cpus
+ */
+ register_cpu_notifier(&cpucache_notifier);
+
+
+ /* The reap timers are started later, with a module init call:
+ * That part of the kernel is not yet operational.
+ */
}
int __init cpucache_init(void)
{
- kmem_cache_t *cachep;
int cpu;
- down(&cache_chain_sem);
- g_cpucache_up = FULL;
-
- list_for_each_entry(cachep, &cache_chain, next)
- enable_cpucache(cachep);
-
/*
* Register the timers that return unneeded
* pages to gfp.
*/
-
for (cpu = 0; cpu < NR_CPUS; cpu++) {
if (cpu_online(cpu))
start_cpu_timer(cpu);
}
- up(&cache_chain_sem);
return 0;
}
--- 2.5/init/main.c 2003-05-06 21:01:41.000000000 +0200
+++ build-2.5/init/main.c 2003-05-06 21:04:10.000000000 +0200
@@ -424,7 +424,6 @@
*/
console_init();
profile_init();
- kmem_cache_init();
local_irq_enable();
calibrate_delay();
#ifdef CONFIG_BLK_DEV_INITRD
@@ -437,7 +436,7 @@
#endif
page_address_init();
mem_init();
- kmem_cache_sizes_init();
+ kmem_cache_init();
pidmap_init();
pgtable_cache_init();
pte_chain_init();
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